Features of the reaction of 4-bromobut-2-enylphosphonium salts with monosubstituted hydrazines

(4-Bromobut-2-en-1-yl)triphenylphosphonium bromide reacted with phenylhydrazine at 2°C in the presence of sodium carbonate to form triphenyl[4-(2-phenylhydrazinylidene)but-2-en-1-yl]phosphonium bromide in 62% yield. The obtained N-phenylhydrazine derivatives cyclized into the corresponding pyrazoline derivatives of phosphonium salts. Unlike phenylhydrazine, ethylhydrazine reacted with (4-bromobut-2-ene-1-yl)triphenylphosphonium bromide under the same conditions to afford triphenyl[(1-ethyl-4,5-dihydro-1Hpyrazol-3-yl)methyl]- and -[(1-ethyl-1H-pyrazol-3-yl)methyl]phosphonium bromides in yields of 60 and 40%.     

A remark on KL → 2μ decay and possible existence of new particles

The possibility of production of new particles in yet unobserved decay channels of the K_L meson is discussed in connection with the K_L → 2μ puzzle. Experimental possibilities of searching for these particles are considered.     

Completely solvable imbedding problems with Abelian kernel for local fields

The imbedding problem for p-groups is considered in which the fields are assumed to be local and the kernel commutative. Additional conditions are investigated under which a solvable imbedding problem has a field as solution. Sufficient conditions are found for such solvability in the form of inequalities imposed on the number of generators of certain groups.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova AN SSSR, Vol. 75, pp. 67–73, 1978.     

Sonogashira reaction of 5-substituted 3-(prop-2-yn-1-yl)oxolan-2-ones

Palladium-catalyzed cross-coupling of 5-methyl- and 5,5-dimethyl-3-(prop-2-yn-1-yl)oxolan-2-ones with dihaloarenes (dihaloheteroarenes) gave mixtures of the corresponding mono- and bis-coupling products. The latter can be obtained as the major products by variation of the catalytic system.     

Rearranged series by Haar system

For the orthonormal Haar system {X _n} the paper proves that for each 0 < ? < 1 there exist a measurable set E ? [0, 1] with measure | E | > 1 ? ? and a series of the form Σ _n=1 ^∞ a _n X _n with a _i ↘ 0, such that for every function f ∈ L ¹(0, 1) one can find a function \(\tilde f\) ∈ L ¹(0, 1) coinciding with f on E, and a series of the form

$\sum\limits_{i = 1}^\infty {\delta _i a_i \chi _i } where \delta _i = 0 or 1$

, that would converge to \(\tilde f\) in L ¹(0, 1).

     

Molecular properties of modified chitosan containing a quaternary amino group

A homologous series of the chitosan derivative N-[(2-hydroxy-3-trimethylammonium)pro-pyl]chitosan in a 0.33 M CH₃COOH + 0.2 M CH₃COONa mixture is studied via viscometry and static and dynamic light scattering. The molecular masses of the homologous series are determined, and the scaling relationships for the intrinsic viscosity, translational-diffusion coefficient, and hydrodynamic radius of molecules are derived. For the mentioned polymer-solvent system, the mean hydrodynamic invariant is estimated as A ₀ = (3.4 ± 0.1) × 10⁻¹⁵ kg m²/(s² deg mol^1/3). The equilibrium thermodynamic rigidity of modified chitosan chains is found to be 20 ± 2 nm. This value, like the parameters of the scaling relationships, suggests that the chitosan derivative under investigation belongs to the class of rigid-chain polymers. It is shown that, in the selected mixed solvent, the molecules of the modified chitosan are more compact than molecules of its nonmodified analog having close degrees of polymerization.     

Specific Small Molecule Inhibitors of Skp2-Mediated p27 Degradation

1. Download : Download high-res image (282KB)
2. Download : Download full-size image

Highlights? In silico screening against a pocket formed by the Skp2-Cks1 protein interface ? Structure-based discovery of Skp2 ligase inhibitors that block p27 ubiquitylation ? Inhibition of Skp2 ligase activity stabilizes p27 protein in melanoma cells ? Inhibitor induction of p27 results in cell cycle arrest in various cancer cells     

On compact quantum semigroup QS red

We study some properties of a reduced semigroup C*-algebra of a semigroup S. For the semigroup C*-algebra generated by the deformation of the algebra of continuous functions on a compact abelian group we obtain a structure of a compact quantum semigroup. We also consider morphisms of constructed compact quantum semigroups.